Digital method for matching stains

ABSTRACT

The present invention relates to color matching and, more specifically, an apparatus and method for preparing a stain to match a target color of a selected substrate (e.g., wood species). In one embodiment a system is provided that comprises (i) a computer (e.g., a stand-alone PC or a networked computer), (ii) hardware and/or software to store a database of stain records, (iii) hardware and/or software to create or load spectral data (e.g., a digital image) of a target sample, and (iv) hardware and/or software to display images and/or process spectral data. The system preferably facilitates the selection of a desired stain, and in preferred embodiments may also include hardware and/or software to dispense colorant agents and/or vehicles to create the desired stain. The system of the present invention may be used in a “manual” mode (whereby a human compares database and target images and makes a selection); an “automatic” mode (whereby the computer system uses spectral data to suggest a closest match based on the selected substrate); or a “combination” mode (whereby the computer system uses spectral data to suggest a closest match and the user can then compare the suggested match with various images to achieve a final selection).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. provisional patentapplication Ser. No. 60/663,294, filed Mar. 18, 2005, which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to color matching and, more specifically,an apparatus and method for preparing a stain that when applied to aselected substrate (e.g., a wood stain applied to a selected woodspecies) will match a target color.

BACKGROUND

Paints and stains are often used to protect and/or decorate a surface.Stains are transparent or semitransparent solutions or suspensions ofcoloring agents (such as, for example, dyes or pigments and the like) ina vehicle, and typically are designed to color a surface without hidingit or leaving a continuous film. As a result, the stained substrate(typically a species of wood) is colored, but the grain pattern isgenerally not hidden. In contrast, paints are usually opaque solutionsor suspensions of coloring matter in a carrier, designed to hide orcover a surface with an opaque film.

Computerized color matching techniques using spectrophotometers are usedwith paints. However, the use of computerized color matching techniqueswith transparent or semitransparent stains has not been successful, dueto the transparent or semitransparent nature of stains, the wide varietyof available substrates (e.g., wood species, each of which imparts itsown contribution to the color), and the variations of color within evena single substrate sample.

Instead, transparent or semitransparent stains are conventionally colormatched, if at all, using a trial-by-error method. In one suchtrial-by-error method, a colorist inspects the color of the stainstandard and then guesses regarding the pigments and relativeconcentrations of same necessary to provide a color matching stain. Astain is then prepared based on the pigment and concentration guesses.The stain is applied to a substrate and then the stained substrate iscompared to the stain standard. If the visual inspection indicates thatthe stain standard and the stained substrate do not match, the coloristguesses at the amount of pigments to add to the stain and the new stainis applied to the substrate. These steps are repeated until the coloristdetermines that there is a color match. As can be appreciated, such atrial-by-error method is tedious and relies upon the skill of thecolorist for its effectiveness.

The aforementioned method is not at all practical for do-it-yourselfers,mass merchants or home center staffs. Instead, the customer is usuallyrequired to select the closest “color” from a very limited palette ofpre-mixed stains. For example, color matching may be conducted bycomparing a stained article (target) to a limited number of coloredsamples, usually between about 15 and about 20, on a display rack havinga very limited selection of substrates. The limited choices are oftennot close enough for good color matching; resulting in a veryunsatisfactory experience for many customers. Moreover, the differencesin the base color (background) of different substrates (e.g., woodspecies) make it difficult to obtain good matching of a color of thestain on different substrates or types of wood.

Accordingly, there is a need in the art for an improved method of colormatching transparent or semitransparent stains and an apparatus that canselect, suggest, and/or prepare an accurate color match for stains fordifferent substrates, e.g., different wood species. The presentinvention is directed to such a method and apparatus.

SUMMARY

The present invention provides an apparatus and method for selecting;

suggesting and/or preparing a wood stain to color a wood species tomatch a target color.

In one embodiment, the method comprises the step of providing a computersystem that contains a database of stain information, wherein thedatabase preferably contains a plurality of records associated withstains, each record including: (i) a stain formula representing a stain,and (ii) at least one of: (a) a digital color image depicting the stainas applied to one or more substrates; and (b) spectral data for thestain as applied to one or more substrates. The method also comprisesthe steps of: obtaining at least one of (a) a digital color image of atarget object and (b) spectral data of a target object; specifying asubstrate to be stained; and selecting a desired stain and associatedformula by comparing at least one of (a) the digital color image of atarget object and (b) the spectral data of a target object to thedatabase records associated with the specified substrate.

In another embodiment, the method comprises the step of providing acomputer system that includes a color monitor and contains a database ofstain information, wherein the database preferably contains a pluralityof records associated with stains, each record including: (i) a stainformula representing a stain, and (ii) at least one of: (a) a digitalcolor image depicting the stain as applied to one or more substrates;and (b) spectral data for the stain as applied to one or moresubstrates. The method also comprises the steps of: specifying asubstrate to be stained; displaying on the monitor at least one of (i)the digital color image of a stain record for the selected substrate and(ii) a color image representing the spectral data of the stain for theselected substrate; and selecting a desired stain and associated formulaby comparing a target object to the displayed record image.

In one embodiment, the apparatus includes data (e.g., spectral data,colored digital images, etc.) for a plurality of colored stains asapplied to a plurality of included substrates (e.g., wood species); adevice (or devices) for displaying, measuring and/or imaging the targetcolor; and a processor configured to suggest or facilitate the selectionof the formula for a stain as applied to a specified substrate. Theapparatus may be configured to execute a set of instructions to dispenseat least one ingredient (e.g., colorant composition) to prepare a liquidstain designed to closely match the target color on the selectedsubstrate. The apparatus can provide stains based on pre-determinedformulas for specific stain colors, or in preferred embodiments it mayprovide custom stain colors.

In another embodiment, the apparatus includes data (e.g., spectral data,colored digital images, etc.) for a plurality of colored stains asapplied to a plurality of included substrates; and a device (or devices)for displaying the colored digital images. A user may compare a physicaltarget specimen to the displayed images, and in preferred embodiments aprocessor is configured to facilitate the selection of the formula for astain as applied to a specified substrate.

In one embodiment, the apparatus includes a database containing data fora variety of colored stains as applied to a plurality of substrates(e.g., wood species). The system can determine or facilitate thedetermination of the amount of colorant agent required to prepare astain to color a specific substrate to match a target color. The targetcolor can be a stained wood species which can be the same or differentthan the selected substrate (e.g., wood species).

In one embodiment, an untinted stain carrier is provided in a container(e.g., a can) and the apparatus can dispense suitable colorantcomposition into the container to tint the stain to a desired color.Alternatively, the apparatus can include one or more carriers for stainsand dispense the carriers into a container. An advantage of theapparatus of the invention is that it allows for the accuratepreparation of small tinted stain samples, e.g., from about 2 to 4ounces (57 to 114 ml), as well as larger amounts. Regardless of size,the stains can be prepared with a high degree of accuracy that willallow accurate color matching.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The details of one or more embodiments of the invention areset forth in any accompanying drawings and the description below. Otherfeatures, objects, and advantages of the invention will be apparent fromthe description and drawings, and from the claims.

DEFINITIONS

The terms “preferred” and “preferably” refer to embodiments of theinvention that may afford certain benefits, under certain circumstances.However, other embodiments may also be preferred, under the same orother circumstances. Furthermore, the recitation of one or morepreferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. Thus, for example, a stain that comprises “a”pigment can be interpreted to mean that the stain includes “one or more”pigments.

As used herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.).

As used herein, the term “stain” refers to a transparent orsemitransparent solution or dispersion of coloring matter (such as ofone or more pigments, colorants, tinting agents, dyes and/or metaleffect agents), plus various optional stain additives (e.g., fillers andextenders) in a vehicle (e.g., binder and thinner). Wood stains can beoil-based or water-based. Typically, a stain is transparent orsemitransparent and designed to color a substrate such as a piece ofwood without totally hiding it or leaving an opaque film. Stains usuallywill have low solid content relative to paint, e.g., frequently thesolids can be less than about 20 percent by weight. The term “stain”also refers to “varnish stains” or “one step stain coatings,” i.e., aproduct that can provide both a color (stain) to the wood and a finishcoating in a single application. Hereinafter, unless otherwise noted,any reference to “stain” means both stain and coating. Non-limitingexamples of finishes include varnishes, shellacs, polyurethanes, teakoil, linseed oil water-based dispersions and emulsions such as, forexample, acrylic emulsions or polyurethane dispersions, and the like.

As used herein, a “transparent stain” is meant to include colored stainsthat are permeable to visible light and are not opaque. As used herein,a “semi-transparent stain” is meant to include colored stains that arepartially transparent or are translucent, but which are not totallyopaque.

A latex or emulsion stain (“latex stain”) is a water-based stain rangingin viscosity from a thin liquid to a semi-solid paste and includes aresin dispersion, water, one or more pigments, colorants, tinting agentsand/or metal effect agents, and other optional additives (e.g., fillersand extenders). Water-based stains typically have waterborne binderssuch as acrylic emulsions and water dilutable alkyds. A “latex stain”includes one step coating products such as, for example, a water-basedpolyurethane having a stain component.

An organic solvent-based stain (“solvent stain” or “alkyd stain”) is auniformly-dispersed mixture ranging in viscosity from a thin liquid to asemi-solid paste and includes a polymeric binder; an organic solventcarrier (such as but not limited to mineral spirits, VMP naphtha,kerosene, xylene, lacquer solvents such as acetone or other ketones,toluene or a mixture of these); one or more pigments, colorants, tintingagents and/or metal effect agents; and other optional additives (e.g.,fillers and extenders). The polymeric binder can be a drying oil,natural, semi-synthetic or synthetic resin such as polyacrylate,polyurethane, modified alkyd resin or other film-forming polymer.Included as well in the binder usually is a cross-linking agent,hardener, curing agent and/or secondary resin having cross-linkingability. A “solvent stain” or “alkyd stain” includes one step coatingproducts such as, for example, a solvent-based polyurethane having astain component.

Typically, the stains prepared using the apparatus of the inventioninclude a “carrier” or “vehicle.” The “carrier” or “vehicle” includesthe finish coating materials such as, for example, varnishes, shellacs,polyurethanes, teak oil, linseed oil and the like. As used herein, theterm “carrier” or “vehicle” shall mean a binder and one or more optionalthinners and other ingredients (excluding colorant agents) used to formstains.

A “pigment,” is a substance that imparts color to another substance ormixture and is usually in the form of organic or inorganic dry powder. A“Colorant” is also a substance that imparts color to another substanceor mixture, and generally includes at least one pigment and otheradditives. “Dyes” and “Tinting agents” similarly are color-impartingagents. “Metal effect agent” is an agent that imparts metallic-typeluster, pearlescent effect agents and associated properties to stainfilms. Hereinafter, unless otherwise noted, pigment, colorant, tintingagent, dye and metal effect agent will be referred to collectively as“colorant agent.”

In general, pigments are insoluble in the vehicle, whereas dyes aresoluble in the vehicle. Inorganic pigments include metal oxides such asthe oxides of iron, titanium, zinc, cobalt, and chrome. Various forms ofcarbon may be used for black pigments. Organic pigments may be derivedfrom natural or synthetic materials, and include but are not limited tophthalocyanine, lithos, toluidine, and para red. Organic pigments may beemployed in a precipitated form as a lake. Dyes are generally organicmaterials and include dyes such as gilsonite; acid dyes, such as azo,diazo and triarylmethane dyes; and basic dyes, such as aniline dyes. Inaddition, chromium salts, iron salts and cobalt salts may be used.

Pigment-based colorants are often provided in the form of “tintingconcentrates” or “colorant compositions” comprising highly concentratedlevels of colorant agent dispersed into a vehicle (typically furthercomprising a surfactant package to promote the storage stability of thecomposition). The amount of colorant agent used in a colorantcomposition is typically from about 5 weight percent to about 70 weightpercent, depending on the type of colorant agent.

DETAILED DESCRIPTION

The present invention is directed to a method of color matching stainsand a computerized system that permits the selection or production of astain that when applied to a substrate closely matches a target color.The system is designed to accommodate a variety of wood species andother types of absorbent or porous substrates (e.g., engineered buildingmaterials such as grain pattern printed paper-faced boards, cement-basedbuilding materials, textured plastics, etc.).

More specifically, the present invention is directed to a method ofselecting or producing (e.g., tinting a stain base) a stain that whenapplied to a desired substrate (e.g., a wood species) will have the sameor substantially the same color as a target object. The method of thepresent invention may be used for both oil-based and water-based stains.The method may be used to select a particular stain from a set ofpre-existing stains, or produce a stain, for example, by tinting a stainbase.

In one embodiment of the present invention, a system is provided thatcomprises (i) a computer (e.g., a stand-alone PC or a networkedcomputer), (ii) hardware and/or software to store a database of stainrecords, (iii) hardware and/or software to create or load spectral data(e.g., a digital image) of a target sample, and (iv) hardware and/orsoftware to display images and/or process spectral data. The systempreferably facilitates the selection of a desired stain, and inpreferred embodiments may also include hardware and/or software todispense colorant agents and/or vehicles to create the desired stain.

As will be discussed in more detail below, the system of the presentinvention may be used in (i) a “manual” mode (whereby a human comparesdatabase images to a physical specimen or to target images. and thenmakes a selection); (ii) an “automatic” mode (whereby the computersystem uses spectral data to suggest a closest match based on theselected wood species); or (iii) a “combination” mode (whereby thecomputer system uses spectral data to suggest a closest match and theuser can then compare the suggested match with various images to achievea final selection). In one embodiment of the manual mode the spectraldata is not used. Rather, only color images are being compared.

The apparatus of the invention can be used to prepare a stain for a widevariety of species of substrates (e.g., wood) that may be included inthe system. Non-limiting examples of specific wood species that may beincluded in the system include white oak, red oak, white pine, southernyellow pine, poplar, spruce, cherry, walnut, redwood, cedar, maple,mahogany, birch, hickory, walnut, ash, and the like. Preferably the woodspecies that are included in the system include at least red oak, whitepine, and birch. More preferably the included wood species in the systeminclude at least red oak, birch, cherry, maple and white pine. Inaddition, the system may include variations of these species (e.g., aheavily grained white oak,, a moderately grained white oak, a relativelygrain-free white oak, etc.). In addition, the system may include otherabsorbent or porous substrates such as cement- orfiber-reinforced-cement-based products, printed paper veneered buildingmaterials, etc.

In one embodiment, the invention provides an apparatus that suggests astain formula for the selected substrate by selecting (or permitting theselection of) a formulation that will result in the closest color matchfrom the database. The apparatus may optionally determine the closestformula by performing calculations (e.g., interpolation) to prepare anew formulation different from the closest pre-existing color match inthe database.

In one embodiment, the present invention relates to an apparatus thatcan prepare solvent- and water-based stains for application to aspecified substrate (e.g., wood species) wherein the prepared stains arevisually match the target color. The apparatus of the invention uses astain matching computer program that can analyze the color data from thetarget. When used in connection with wood substrates, this allows theapparatus to identify a suitable color and prepare a suitable stain tomatch the target color on any type of wood, or prepare a stain havingthe same stain color on two different species of wood, i.e., match thecolor on two different species of wood. For example, a stain can beprepared to match the color for oak trim to the color of a maplecabinet. The apparatus allows the “reading” of a maple stain color(target color) and, the generation of a stain color to match the oaktrim to the maple color.

In one embodiment, the apparatus of the invention includes data (e.g.,spectral data and/or digital color images) for a plurality of coloredstains as applied to a plurality of substrates (e.g., wood species).These data may be prepared, for example, by staining various species ofwood (or other substrates) with several color stains and measuring thecolor of the stained wood (or portions of the stained wood) and/ortaking a digital color image of the stained wood. An optional topcoat,such as a clear finish may be applied to the stained wood samples. Anynumber of stained samples for each wood species can be prepared. Forexample, it may be useful to prepare from about 100 to about 400 coloredsamples for each included wood species. In general, having a sufficientnumber of included colored stained samples will facilitate the selectionof a matching stain foraparticular wood species.

As will be described more fully below, in one embodiment the colormatching software program includes a database (or plurality ofdatabases) containing spectral data for stain products applied todifferent substrates. The color matching software program also containsone or more formula(s) for wood stain composition(s) describing therequired proportions of vehicle, colorant agents, and other additives.

The catalogued substrates that are used to determine the spectralcharacteristics of the stains preferably include panels composed ofdifferent types of woods such as the species mentioned herein.

A typical database record will contain (i) a stain formula (i.e.,sufficient information to select a pre-determined stain or to produce astain from various ingredients); and (ii) one or both of (a) a digitalcolor image depicting how the stain would appear as applied to one ormore substrates (e.g., wood species), and (b) spectral data associatedwith the stained substrate (e.g., spectral data representing the colorof the stained wood or portions thereof).

The database may be assembled in a variety of ways. In one embodiment, aseries of known stain formulas are applied to a variety of differentwood species. The stained wood samples are then imaged or measured. Inthis embodiment, it is likely that the different wood types will yield apalette of colors that differ. However, it is also possible that similarcolors may be found in the palette (i.e., formula A on wood species Imay produce a similar color to Formula B on wood species II). In anotherembodiment, a palette of colors is created using a single species ofwood and a colorist then uses a trial-and-error methodology to “match”those colors on other wood species by adjusting the formulas. In thiscase, the color palette will be uniform, but the formulas to achievethose colors will vary depending on the wood species selected. Acombination of these two methods may also be used to create thedatabase. Preferred databases have sufficient breadth of information toassist a user in finding the right formula of stain for the desiredcolor and substrate.

Preferred systems for creating a digital image of a stained panelinclude (i) a camera (preferably a digital camera) and optional lightsource or (ii) a digital scanner. Care should be taken when creating adigital color image of a stained panel to ensure that the stored and/ordepicted color of the image accurately reflects the perceived true colorof the panel. The choice of lighting used during image capture may be ofsome importance in this regard.

If desired, the panel image may be taken under the same conditions as anassociated image of a color reference. For example, the panel may beplaced adjacent one or more standard color reference panels. This wouldensure that the panel and the reference panel images are exposed to thesame conditions and the captured colors of the panel image may besuitably corrected, if necessary, using standard color correctionalgorithms (L e., a correction may applied to correct the referenceimage to its true color and the same correction may be then applied tothe panel image). This same technique may be used when measuring theimage of a target panel. Preferably, the database panel images and thetarget panel images should reflect similar imaging processes. When woodpanels are being compared it is also desirable to use a similarmagnification power. This will make the grain patterns appear roughlythe same size and avoid any potential perception bias that may beintroduced by differences in grain size appearance.

The digital color image of a stained panel (of either the databaseimages or the target image) may then (or later) be analyzed. Spectraldata of various portions of the image may be cataloged or calculated. Asdescribed in the 1991 National Forest Products Association brochure, atree typically goes through two distinct periods of growth, resulting intwo bands called “earlywood” (sometimes referred to as “springwood”) and“latewood” (sometimes called “summer wood”). The earlywood is generallylighter and less dense than latewood and these two portions accept stainat a different level. It has been discovered that the portions of theimage that depict “earlywood” may be particularly important in theperception of the overall “match.” Consequently, in preferred methodsthe spectral data from the earlywood regions are particularlyinteresting. The color data from these regions may be sampled on apixel-by-pixel basis, if desired. Alternatively, a digital filter may beapplied to the image (or a portion of the image) to capture the desireddata. In one embodiment, the pixel colors are analyzed and statisticallyprocessed to capture the desired data. For example, a histogram of thecolor data values may be prepared and the light “earlywood” regionsidentified.

In one embodiment, the digital color image is taken with a light sourcethat will represent the target under the desired lighting conditionsthat is most suitable for a realistic match. If desired, databases thatrepresent the stain colors under different lighting conditions (e.g.,indirect daylight, fluorescent, etc.) may be stored and the desired“match conditions” selected by the user. In addition, databases thatrepresent the stain colors and a variety of topcoat finishes may bestored and the user may select the desired topcoat finish.

As an alternative, suitable “synthetic” digital images may be producedto populate the database. In this embodiment, a digital image of a woodpanel is created and “colored” appropriately to represent how theparticular species of wood would look when stained with a given stain.One advantage of this method of populating the database is that fewerimages need to be taken and the user will see the stain as applied tothe same piece of wood. In other words, the same grain pattern will bedisplayed no matter what color stain is selected. This will helpeliminate bias that might be introduced if different grain patterns areshown. One method of achieving this database is to select those portions(e.g., those pixels) of the image that comprise the light earlywoodcolor and color them with the appropriate color for that type of wood.The dark latewood portions can be appropriately colored for each recordimage.

Suitable cameras for use in the present invention include analog ordigital cameras such as are manufactured by a wide variety of companies.Digital cameras are preferred as their use eliminates the need toprocess a film and/or convert the film image to digital information. Ifdesired, the cameras may be fitted with a flash device, preferably aflash that is color balanced with the detector. In one embodiment theflash device is in the form of a ring around the lens. See, e.g., theKodak DX7590 camera. This enables the flash to uniformly illuminate atarget and not cast shadows of create uneven illumination of the target.

Suitable such scanners include high quality color “flat-bed” scannersthat are available from a variety of companies.

If desired, the system may optionally include a spectrophotometersuitable for measuring spectral data of stained wood. Suitablespectrophotometers include a device for separating light into itscomponent wavelengths, such as a diffraction grading or a prism, and anarray of detectors to measure the intensities of the differentwavelengths. This type of device is often used for color identificationand there are suitable models available, which are designed to identifycolors. Examples of suitable spectrophotometers include the CF-57U,CF57)(45°/0°) or CFS57 (sphere D/8°) countertop spectrophotometer(available from Match-Rite). Other examples of suitablespectrophotometers include Datacolor SF-350 and SF-600spectrophotometers.

The spectrophotometers used for color matching are usually designed tosimulate the human eye's system of rods and cones that are used toperceive a color. As a result, the paint industry has typically usedthree-dimensional mathematics to define color space. These variables areoften referred to as (Hue, Value and Chroma), (Hue, Brightness, andSaturation), (x, y, and z), and other descriptive names depending uponthe author. Most color matching programs use this system ofthree-dimensional mathematics to read, record, and create a colordatabase. These programs can be static, in that they provide a closematch to a color offered by a paint company, or interpretive, so thatthe system actually develops a color formula based on complexcalculations as to the effect each colorant has on the final color of apaint or stain.

Typical spectrophotometers for use in measuring paint colors employ a 2cm diameter spot size. It should be recognized that when this spot sizeis used on a stained wood specimen the measured color is an aggregate ofthe colors in that entire area. While this has been appropriate whenmeasuring a uniform paint film, it has been discovered that aggregatingsuch a large area can for some wood species introduce errors in the data(i.e., the dark latewood regions tend to darken the overall measuredcolor, thereby resulting in a “false” match). To avoid these problems asmaller spot size (e.g., 8 mm diameter or less) can be selected and thespot positioned over an earlywood region of the wood panel that avoidsthe dark latewood portions.

The spectral characteristics of the stains (as applied to certaincatalogued wood substrates) may be determined and stored in the computerdatabases using one or more of the following methods. In one embodiment,the spectral characteristics of the applied stains are determined fromreflectance measurements using the Kubelka-Munk Theory. The measurementscan be average values over a broad area (recognizing the limitationsdiscussed above), or may be measurements over smaller selected areas ofthe stained wood (e.g., an area that does not contain late wood).Alternatively, as previously mentioned, the spectral characteristics ofthe applied stains may be calculated by analysis of the digitizedimages. In this later case, one or more pixels is analyzed and the colordata is determined for the selected pixel or pixels.

The system of the present invention preferably contains a color monitor.This monitor is required when the system is being used in the “manual”or “combination” modes. In typical embodiments, the target panel imageis displayed on the monitor adjacent to one or more database images. Theuser is then able to view the images and select or confirm an acceptablematch. It is preferred that the monitor itself displays the colors ofthe images accurately. Of course, small errors in the monitor'sdepiction of the images may be tolerated as both images, database andtarget, will be similarly biased. Monitor calibration accuracy can beimproved using known calibration equipment or techniques. One suitablesystem for calibrating a monitor is the HUEY—COLOR ME ACCURATE systemavailable from Pantone.

One preferred desired output of the system is the selection orproduction of a stain. If the target panel is close in color to anexisting stain product, then the system can simply recommend theexisting stain product. If the target is not acceptably close to apre-existing stain, then in preferred embodiments, the system willprovide instructions how to mix an acceptable stain. In one embodiment,the system outputs a stain formula. This may be a list of base andcolorant compositions that should be mixed together to yield the stain.Alternatively, the system may simply transmit the information directlyto a tinting machine that will then dispense the colorant compositionsand/or stain base to produce the desired stain product.

Suitable tinting machines are available from Fluid Management (e.g., theSeries 7000 machine), Dromont, Corob, or the like.

The invention can use any colorant agents available for preparing stainsknown in the art. These include colorant agents known in the art suchas, for example, dyes or pigments (organic or inorganic). Inorganicpigments include metal oxides such as the oxides of iron, titanium,zinc, cobalt, and chrome and can include mineral pigments obtained fromclay. Non-limiting examples of pigments include titanium dioxide white,carbon black, lampblack, black iron oxide, red iron oxide, transparentred oxide, yellow iron oxide, transparent yellow oxide, brown iron oxide(a blend of red and yellow oxide with black), phthalocyanine green,phthalocyanine blue, organic reds (such as naphthol red, quinacridonered and toluidine red), quinacridone magenta, quinacridone violet, DNAorange, and/or organic yellows (such as Hansa yellow). Organic pigmentsare usually derived from natural or synthetic materials. Organicpigments may be employed in a precipitated form such as, a lake. Dyesare usually organic materials and include dyes such as gilsonite; aciddyes, such as azo, diazo and triarylmethane dyes; and basic dyes, suchas aniline dyes.

In one embodiment, the colorant agents can be universal colorantcompositions, which can provide a single set of colorant formulationsfor use with solvent- and water-based stains. These colorantcompositions are uniform and do not require mixing prior to use, evenafter extended shelf-life. See, e.g., U.S. provisional application, Ser.No. 60/663,040, which is incorporated herein by reference. The typical“shelf-life” for these colorant compositions is about two years.

The colorant agents for practicing the present invention can be obtainedin any form known in the art. Suitable containers for use with colorantcompositions include cans, bottles, pouches, tubes, syringes, andcaulking-type cartridges. In a specific embodiment the colorantcompositions can be provided in sealed pouches wherein the colorantcomposition can be readily dispensed in controlled amounts. Morepreferably, the sealed pouches or containers have a nozzle or adapterorifice that facilitates clean entry of the composition into the tintingmachine. In one embodiment the pouches are provided in boxes for ease ofstorage and use.

Suitable hardware/software for use in the present invention may takemany forms. In general, as used herein a reference to “software” shouldnot be interpreted to exclude or preclude the use of a hardware devicethat is designed to accomplish the same process. For example,image-processing tasks may be handled by software algorithms or inhardware.

Preferred systems of the present invention are designed to input atarget panel image. In one embodiment, the image is taken using a cameraor scanner and digital data reflecting the image is input to the system.The camera or scanner may be physically connected to the system,networked to the system or detached from the system. In the later case,the image data may be provided to the system by appropriate filetransfer methods.

The system preferably should be capable of displaying the target panelimage and one or more database images on a color monitor. Thiscapability is required for “manual” or “combination” mode operation.Typically the system will permit the user to specify the substrate(e.g., wood species) that the stain will be applied to. The selection ofthe substrate will be used by the system (e.g., in the display ofdatabase images on that substrate) in the color matching process. Inaddition, the user may be able to specify the lighting most appropriateto the target panel.

The system is preferably configured to permit the manipulation ofdatabase and/or target images. In one embodiment, the system displays aside-by-side comparison of the target panel image next to a databaseimage. The user is then able to scroll through various database imagesto find the best “match.”

In another embodiment, the system is configured to display an array ofdatabase images surrounding the target panel image. The user can use thevisual clues of the array to better steer through the array and find theclosest “match.”

In yet another embodiment, the system provides “tools” to enable theuser to find other suitable database images. For example, a side-by-sidedisplay of the target panel image and a database image might bepresented. Tools that permit the user to find other images (e.g.,lighter-darker; more red-less red, more green-less green, moregrain-less grain, etc.) are included. By clicking on the selections theuser can be shown other database images that better match the targetpanel image.

In yet another embodiment, the system is configured so that more thanone database image may be selected as “matches.” For example, the usermay decide that the best color is somewhere between database image X andY. The system may be configured to then calculate a formula that is ablend of formulas X and Y.

Once a database image (or images) is selected, the system preferablyprovides a stain formula (either as a printout or as directions to anassociated tinting machine).

In the “combination” mode the system uses spectral data (either from thedigital images or from an associated spectrophotometer scan) to helpguide the user to the best match. In one embodiment, the mostappropriate regions of the database images are compared to the mostappropriate regions of the target panel image. To obtain the mostappropriate regions of the target panel image the user may be guided toselect the appropriate region or filters may be applied to the entireimage to assist or direct that process. For example, in one embodiment,the target panel image is displayed on the monitor and the user ispermitted to select those pixels that he or she would like to match.Alternatively, the computer system can highlight the best regions andget confirmation of this selection from the user.

In another embodiment, if the color of an applied stain (first stain),as applied to the selected species, is not correct, the apparatus can beused to adjust the color of the first stain on the selected species bycomparing the color of the stained substrate after the first stain hasbeen applied to the target color and dispensing additional ingredientsrequired to obtain the desired color. Alternatively, if the originalstain color, as applied to the selected substrate, cannot be modified(e.g., by adding additional colorants) to prepare a new stain color, thecolor information can be used to modify the original formulation andprepare a second stain color.

FIGURES

FIG. 1 a depicts one possible configuration of the system of the presentinvention. In this depiction, system 10 consists of data collectiondevice 30 for measuring a target object 20 a, computer system 40 andoptional tinting machine 60. A suitable data collection device 30 mayinclude cameras 32, scanners 34, spectrophotometers 36, and/or filetransfer devices 38 (not shown). In preferred embodiments the systemincludes a digital camera or scanner. As illustrated, the computersystem 40 includes a processor 42, monitor 44, keyboard 46, and pointingdevice (e.g., mouse) 47. The computer system also includes or isconnected to a storage device (not shown) housing database records 43.The computer system components may be physically connected (e.g., bywires) or the components may be interconnected using wirelesstechnology. Combinations of wired and wireless connections may be used.In addition, one or more of the devices used to form computer system 40may be a networked device.

Any suitable tinting machine 60 may be utilized. Typical machinesinclude one or more ingredient reservoirs 62 and a dispenser 64. Themachine should be capable of delivering known quantities of variousingredients. Preferred systems are in communication with the computersystem 40, but “stand-alone” systems and “manual” systems may also beused. In such instances the desired stain formula information outputfrom the computer system 40 is used to produce the desired stain.

As illustrated in FIG. 1 a, a stained substrate (e.g., wood panel) ismeasured and/or imaged using the data collection device 30. The data isthen transmitted to the computer system 40. In the case where thestained substrate is made using a known stain formula the formula datainformation is associated with the spectral data from the datacollection device(s). In the case of the target panel, the data from thedata collection device is transmitted to the computer system for use inthe matching process. A stain product 70 is selected or produced usingthe system 10 and placed into a suitable container 72. If desired, aprinter (not shown) may be used to create a label for the container.

FIG. 1 b depicts another possible configuration of the system of thepresent invention. In this depiction, system 10 consists of computersystem 40 and optional tinting machine 60. As illustrated, the computersystem 40 includes a processor 42, monitor 44, keyboard 46, and pointingdevice (e.g., mouse) 47. The computer system also includes or isconnected to a storage device (not shown) housing database records 43.In this configuration, a target panel 20 b may be held adjacent themonitor and a comparison of the panel with one or more images may bemade by a user.

FIG. 2 depicts monitor 44 at an illustrative point in one possibleprocess of the present invention and illustrates how information mightbe presented to and/or manipulated by the user. In this illustrativeembodiment, an image 24 is displayed on the monitor. The image 24 is acolor depiction of a stained wood panel having grain lines 24 b. Aregion 24 a of the image may be selected by the system or by the user(e.g., using a pointing device 47). The selected region may be one ormore pixels of the image. The system may be configured to calculate orassemble spectral data regarding the selected region. Furtherillustrated is a menu 82 of substrates (e.g., wood species) that may beselected by the user.

FIG. 3 depicts monitor 44 at an illustrative point in another possibleprocess of the present invention and illustrates how information mightbe presented to and/or manipulated by the user. In this illustrativeembodiment, images 22 and 24 are displayed on the monitor in aside-by-side fashion. Image 24 is a color depiction of a target stainedwood panel and image 22 is a color depiction of a first database stainedwood panel. A software enabled graphical tool 80 is illustrated, wherebythe user may conveniently adjust the database image or selectalternative database images. For example, if the first database image istoo “red”, the user may slide a scroll bar in the direction of less redand the image will be adjusted or replaced with another database imagethat is less red than the first image.

FIG. 4 depicts monitor 44 at an illustrative point in another possibleprocess of the present invention (e.g., at a similar point in theprocess to that discussed in FIG. 3). However, in this illustration, thetarget image 24 is displayed among an array of database images (22 a-22h). Software enabled graphical tools 80 a and 80 b are illustrated,whereby the user may conveniently select alternative database images.For example, if the displayed database images are too “red”, the usermay slide a scroll bar in the direction of less red and the images willbe scrolled to a new less red region of the array.

It is noted that many different graphical representations of coloredpanels may be displayed. The illustrative examples depicted herein areonly a small subset of the ways that are described by this invention.

The merits of the apparatus for preparing the stains of the presentinvention are further illustrated in the following examples.

EXAMPLES Example 1

A stain is applied to a suitable sample of white pine. The stain isallowed to cure and a finish coating, e.g., polyurethane or varnish isapplied. After the finish coating has dried the finished color isoptionally analyzed by a spectrophotometer and the color readingsrecorded in the database.

A digital image of the aforementioned sample is taken using controlledlighting conditions. Care is taken to ensure that the image accuratelyreflects the true color. The image may be taken, for example, using adigital camera or a scanner.

This process is repeated for another shade and the data added to thedatabase. The process is repeated until a sufficient number of colorsfor white pine are recorded in the database.

Example 2

A stain is applied to a suitable sample of red oak. The stain is allowedto cure and a finish coating, e.g., polyurethane or varnish is applied.After the finish coating has dried the finished color is optionallyanalyzed by a spectrophotometer and the color readings recorded in thedatabase.

A digital image of the aforementioned sample is taken using controlledlighting conditions. Care is taken to ensure that the image accuratelyreflects the true color. The image may be taken, for example, using adigital camera or a scanner.

This process is repeated for another shade and the data added to thedatabase. The process is repeated until a sufficient number of colorsfor white pine are recorded in the database.

Example 3

The process described in Examples 1 and 2 can be repeated for any woodspecies (or other porous or absorbent substrate) to be stained andstored in the database.

Example 4

A stain is applied to a suitable sample of white pine. The stain isallowed to cure and a finish coating, e.g., polyurethane or varnish isapplied. After the finish coating has dried the finished color isanalyzed by a spectrophotometer. This process is repeated for anotherstain shade. The process is repeated until a sufficient number of colorsfor white pine are determined.

The color of untreated white pine is then is analyzed by aspectrophotometer. The color readings of untreated pine are subtractedfrom the color readings of the stained samples.

Alternatively, the stain can be applied to a neutral (e.g., white)substrate. The stain is allowed to cure and a finish coating, e.g.,polyurethane or varnish is applied. After the fmish coating has driedthe finished color is analyzed by a spectrophotometer. The neutral staincolor data, representing the actual color of the stain alone, is thenrecorded in the database.

Other species of wood are analyzed by a spectrophotometer in a similarmanner and the data for the colors of the unstained wood species arealso recorded.

After the target color is determined, the ingredients required forpreparing a stain color to match a target color to the selected speciesof wood are calculated using the data for the neutral stain colors andthe unstained wood color.

Example 5a

A target color is analyzed by a spectrophotometer. The processor is usedto determine the closest colors (e.g., two) of stain in the database.The processor calculates the proper formula for the stain byinterpolating between the closest stain colors and their formulas. Thisprocess can be used for either color data for specific species or forneutral stain color data combined with the unfinished wood color data todetermine the finished stain color.

Example 5

A target color is imaged. The user or the system selects the closestcolors (e.g., two) of stain in the database. The processor calculatesthe proper formula for the stain by interpolating between the closeststain colors and their formulas.

Example 6

A target color is analyzed by a spectrophotometer and/or imaged. Thesystem is used to determine the closest of stain color in the database.The apparatus prepares the stain color having the formula. This processcan be used for either the color data for specific species, or forneutral stain color data combined with the unfinished wood color data todetermine the finished stain color.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

All patents, patent applications, and literature cited in thespecification are hereby incorporated by reference in their entirety. Inthe case of any inconsistencies, the present disclosure, including anydefinitions therein will prevail.

1-36. (canceled)
 37. A method, comprising the steps of: providing acomputer system including or connected to a database of staininformation containing a plurality of records associated with aplurality of colored stains, such records including: (a) datarepresenting a transparent or semitransparent stain, and (b) at leastone of: (i) a first digital color image depicting such stain or (i)spectral data for such stain as applied to a plurality of buildingmaterial substrates; and displaying to a user of such system an array ofsuch first digital color images or of second digital color imagesrepresenting such spectral data, the image array depicting a pluralityof colored stains applied to a plurality of building materialsubstrates.
 38. A method according to claim 37, further comprisingdisplaying an image depicting a target object.
 39. A method according toclaim 38, wherein the image array surrounds the target object image. 40.A method according to claim 37, wherein the image array isuser-selectable or user-adjustable.
 41. A method according to claim 37,wherein the image array depicts a plurality of colored stains applied toa plurality of wood substrates.
 42. A method according to claim 41,wherein the image array depicts grain pattern variations for at leastone wood species.
 43. A method according to claim 41, wherein thedatabase records include first digital color image or spectral data fora portion of a wood substrate that contains earlywood and does notcontain latewood.
 44. A method according to claim 37, wherein the imagearray depicts a plurality of colored stains applied to a plurality ofcement- or fiber-reinforced-cement-based building material substrates.45. A method according to claim 37, wherein the image array depicts aplurality of colored stains applied to a plurality of printed paperveneered building material substrates.
 46. A method according to claim37, further comprising outputting a stain formula or dispensing acolorant agent or vehicle to create a desired stain.
 47. A methodaccording to claim 37, wherein the database records include lightingconditions during image or spectral data capture.
 48. An apparatus,comprising: a computer system including or connected to a database ofstain information containing a plurality of records associated with aplurality of colored stains, such records including: (a) datarepresenting a transparent or semitransparent stain, and (b) at leastone of: (i) a first digital color image depicting such stain or (ii)spectral data for such stain as applied to a plurality of buildingmaterial substrates; and a device for displaying to a user of suchsystem an array of such first digital color images or of second digitalcolor images representing such spectral data, the image array depictinga plurality of colored stains applied to a plurality of buildingmaterial substrates.
 49. An apparatus according to claim 48, wherein thedisplaying device also displays an image depicting a target object. 50.An apparatus according to claim 49, wherein the image array surroundsthe target object image.
 51. An apparatus according to claim 48, whereinthe image array is user-selectable or user-adjustable.
 52. An apparatusaccording to claim 48, wherein the image array depicts a plurality ofcolored stains applied to a plurality of wood substrates.
 53. Anapparatus according to claim 52, wherein the image array depicts grainpattern variations for at least one wood species.
 54. An apparatusaccording to claim 52, wherein the database records include firstdigital color image or spectral data for a portion of a wood substratethat contains earlywood and does not contain latewood.
 55. An apparatusaccording to claim 48, wherein the image array depicts a plurality ofcolored stains applied to a plurality of cement- orfiber-reinforced-cement-based building material substrates or applied toa plurality of printed paper veneered building material substrates. 56.An apparatus according to claim 48, further comprising a colorant agentdispenser or vehicle dispenser for creating a desired stain.